1. Field of the Invention
The invention relates to a tape carrier for TAB for mounting an integrated circuit component, an integrated circuit device packaged with an integrated circuit component mounted therein, a method of making the same, and an electronic device.
2. Description of Related Art
Recent liquid crystal display devices use an integrated circuit device having a driver integrated circuit component mounted thereon for the purpose of connecting the LCD cell to its driver circuit. Such an integrated circuit device generally adopts either the TAB method using a so-called TAB package (also known as a TCP (Tape Carrier Package)), or the COG (Chip On Glass) method in which the driver integrated circuit component is directly connected to the glass substrate. Particularly a TAB package has many advantages, being more compact and thinner than other packages, and appropriate for high-density mounting, allowing electrical testing on a tape carrier, and also permitting mounting in a flexed position; for these reasons it has been widely adopted not only for liquid crystal display devices, but also for other electronic devices.
A conventional TAB package, as shown in FIG. 14, has a tape carrier 131 formed of polyimide or the like, in which is formed a device hole 133 of dimensions larger than the dimensions of an integrated circuit component 132 to be mounted thereon. Inner leads 134 projecting within the device hole 133 are connected by way of bumps 135 to electrodes of the integrated circuit component 132. Moreover, to prevent short-circuits between inner leads 134 or contact of the inner leads 134 with the integrated circuit component 132, and to improve reliability, a protective resin 136 covers the inner leads 134 and the surface of the integrated circuit component 132. The electrodes and bumps 135 are normally disposed along the periphery of the integrated circuit component 132, in order that the lengths of the inner leads 134 are as short as possible in the one-sided holding state (that is, in the state where one side only of the inner leads 134 is supported by the tape carrier 131). Additionally, as disclosed in Japanese patent Application Laid-Open No. 63-95639, a construction is also known in which in order to mount an integrated circuit component of large scale and having a large number of electrodes, a lead support portion extending into the device hole is provided on the tape carrier, and some of the leads extend thereover.
However, a conventional TAB package as described above has a gap between the peripheral edges forming the device hole 133 and the peripheral edges of the integrated circuit component 132, and the protective resin 136 is provided in order not to expose the inner leads 134 in this gap. As a result, the outer dimensions of the package are considerably larger than the outer dimensions of the integrated circuit component 132 and the mounting area is increased. Additionally, with the miniaturization of the integrated circuit component 132, and a closer pitch for the electrodes and inner leads 134, connecting leads 134a supported on the tape carrier 131 are required to be finer, and a large area is required to bring out the connecting leads 134a since the wiring distance is increased. For this reason, the area of tape carrier used for mounting a single integrated circuit component 132 is increased, the overall package dimensions are further increased, and the mounting area is increased, resulting in a problem of going against the requirement to make the electronic apparatus more compact.
In particular, in the case of a liquid crystal display, as shown in FIG. 15, a plurality of TAB packages 138 (only one of which is shown in the figure), each having a driver integrated circuit component 137 mounted thereon, is connected along the periphery of an LCD cell 139, and further on the outer side thereof is connected a printed circuit board 140 forming a drive circuit. With respect to the overall dimensions of the liquid crystal display device, to increase the liquid crystal display area, it is necessary to reduce the width W of the so-called frame portion. For this purpose, it is necessary, while reducing each of the width w1 of the outer periphery 141 of the LCD cell 139 connected to the TAB package 138 and the width w2 of the printed circuit board 140, to make the TAB package 138 smaller, and thus to reduce its width w3. For this purpose, it is possible first to consider making the driver integrated circuit component 137 smaller, and reducing the corresponding width as much as possible, but in a TAB package of the above-described conventional construction, it is difficult to go smaller than the current size, and there is a problem that the width W of the frame portion cannot be adequately reduced. On the other hand, with the COG method, the connection leads are also formed at the periphery of the LCD cell 139 in addition to a driver integrated circuit component being directly mounted, and it is therefore more difficult to reduce the width W of the frame portion than in the TAB method.
Additionally, with the increasing compactness of electronic apparatus another problem arises. For example, with the move to fine high output pin counts, one of integrated circuit components, employed in a liquid crystal display device or the like, has an elongated shape and electrodes disposed in two rows along its long dimension with wires a lead-out in two directions. Such an integrated circuit component and tape carrier are shown in FIG. 16. In this figure, an integrated circuit component 142, and inner leads 144 formed on a tape carrier 143 are connected by thermal bonding by a bonding tool (thermal bonding tool) not shown in the drawing. Here the tape carrier 143 has a large coefficient of thermal expansion with respect to the integrated circuit component 142. For this reason, when the two are subjected to thermal bonding, the tape carrier 143 is thermally bonded in the extended state to the integrated circuit component 142. However, after the thermal bonding, since the tape carrier 143 shrinks with the fall in temperature, the tape carrier 143 pulls the inner leads 144, and the tape carrier 143 is deformed in an arc shape in the vicinity of the integrated circuit component 142. Moreover, as the tape carrier 143 pulls the inner leads 144, there is a possibility of breakage of the inner leads 144.
The object of the invention is to provide a tape carrier, integrated circuit device, a method of making the same, and an electronic device, enabling miniaturization of electronic apparatus, solving the problems occurring with the miniaturization of electronic apparatus.
(1) The tape carrier of the invention for TAB comprises a base material having an insulating property and an elongated shape. The base material has peripheral edges defining an opening for disposing an integrated circuit component. A first pair of portions of the peripheral edges face each other. A second pair of portions of the peripheral edges face each other. A plurality of connection leads extend from the first pair of portions into the opening. At least one dummy lead extends from the second pair of portions into the opening.
According to the invention, after the integrated circuit component is mounted, the base material which has been heated tries to contract, but the dummy lead provided projecting in the direction of contraction supports the base material. As a result, breakage of the connection leads by shrinkage of the base material can be prevented.
Here, the term xe2x80x9cdummy leadxe2x80x9d refers to any part which is not used for transmitting or receiving signals or the like, and has no electrical function, and is not particularly concerned with whether or not there is a connection to an electrode of the integrated circuit component.
(2) Some dummy leads may extend from each of the second pair of portions.
(3) The dummy lead may have a width narrower than a width of each of the connection leads.
By this means, the dummy lead is made finer, but because of the dummy lead, the force generated by the contraction of the base material can be withstood. Besides, since the dummy lead is fine, when the sealing material is injected after mounting the integrated circuit component, the sealing material is able to flow positively to the rear of the dummy lead, and residual air bubbles can be prevented.
(4) The dummy lead may have a projection, which is formed in a direction substantially perpendicular to an extending direction of the dummy lead.
By this means, when the sealing material is injected after mounting the integrated circuit component, surface tension is created in the interval between the projection and the integrated circuit component, and an excessive flow of the sealing material from the gap between the integrated circuit component and the opening can be prevented. For this reason the thickness of the sealing material can be made uniform.
(5) The dummy lead may be formed on one surface of the base material and have a bending portion bent toward the other surface of the base material. The projection may extend from the bending portion of the dummy lead.
By this means, since the difference in height between the projection and the integrated circuit component can be assured, an adequate surface tension of the sealing material can be obtained using the difference in height. Besides, since the bending portion produces a difference in height, the projection can be formed to be longer, within a given distance, compared with the case of a flat shape. For this reason, an excessive flow of the sealing material into the opening can be prevented, and the thickness of the sealing material can be made uniform.
(6) The width of the dummy lead may be wider than a width of each connection lead.
By this means, even when the peripheral edges around the opening into which the plurality of connection leads extend are cooled and the opening seeks to expand, this force can be withstood without dummy lead breaking.
(7) The connection leads may extend along a longitudinal direction of the base material, and the dummy lead may extend in a direction substantially perpendicular to an extending direction of the connection leads.
By this means, the connection leads can be brought out in the longitudinal direction of the base material without bending, and the area of the base material can be used effectively.
(8) The integrated circuit device of the invention comprises a base material having an insulating property and having an opening. A plurality of connection leads are provided on the base material. The connection leads extend into the opening. An integrated circuit component is connected to the connection leads inside the opening. The integrated circuit component includes a first portion and a second portion. The first portion is positioned inside of the opening and provided with a plurality of electrodes electrically connected to the connection leads. The second portion faces a portion of the base material. At least one of the connection leads is provided on the portion of the base material to which the second portion faces.
By this means, since the first portion of the integrated circuit component to be positioned in the opening is smaller than the opening, a gap is formed between the peripheral edges of the opening and the first portion. As a result, in the first portion exposed through the opening, flowability of the sealing material on the integrated circuit component is assured, and in the gap between the peripheral edges of the opening and the first portion, the sealing material flows onto the opposite surface. In addition to this advantage, since the connection leads can be provided in the area where the second portion of the integrated circuit component and the base material oppose each other, the external dimensions of the integrated circuit device can be made smaller than in the conventional case.
(9) The pitch between a pair of the connection leads is converted in the portion to which the second portion of the integrated circuit component faces.
By this means, pitch conversion of the connection leads can be carried out in the area in which the projections of the integrated circuit component and the base material overlap, and therefore the external dimensions of the integrated circuit device can be made smaller than in the conventional case.
(10) The outline of the opening may be smaller than the outline of the integrated circuit component.
By this means, the area in which the integrated circuit component faces the base material is increased, whereby this area can be used as a connection lead pitch conversion region, or can be used as a region for bringing out the connection leads, and the freedom of design of the connection leads is increased. Besides, since connection leads can be formed in the area of the base material facing the integrated circuit component around the periphery of the opening, the external dimensions of the overall base material can be made smaller than in the conventional case.
(11) The integrated circuit component may have an oblong shape. The first portion may have an edge portion forming one of the long sides of the oblong shape. The electrodes of the integrated circuit component may be disposed in one row along the long side.
By this means, the connection leads may be disposed in the direction perpendicular to the longitudinal direction of the integrated circuit component, and the connection leads can be made shorter.
(12) The integrated circuit component may have an oblong shape. The first portion may have an edge portion forming one of the long sides of the oblong shape. The electrodes of the integrated circuit component may be disposed in two rows along the one of the long sides.
By this means, while reducing the dimensions of the base material, the electrodes of the integrated circuit component can be disposed in accordance with the number of electrodes, the conditions of connection with the exterior device and circuits, and so forth.
(13) The integrated circuit device of the invention may further comprise a sealing material sealing at least connection portions between the electrodes of the integrated circuit component and the connection leads. At least one dummy lead may extend into the opening. The opening may be formed by peripheral edges. The dummy lead may extend from at least one of a pair of the peripheral edges facing each other. The connection leads may extend into the opening from the other pair of the peripheral edges facing each other.
By this means, after the integrated circuit component is mounted, the heated base material shrinks in the direction of the electrode disposition of the integrated circuit component, and the opening seeks to expand, but the dummy lead extending in this shrinking direction supports the base material. As a result, breakage of the connection leads can be prevented.
(14) The dummy lead may have a width narrower than a width of each connection lead.
By this means, the dummy lead is made finer, but because of the dummy lead, the force generated by the contraction of the base material can be withstood. Besides., since the dummy lead is fine, when the sealing material is injected after mounting the integrated circuit component, the sealing material is able to flow positively to the rear of the dummy lead, and residual air bubbles can be prevented.
(15) The dummy lead may have a projection. The projection may be formed in a direction substantially perpendicular to an extending direction of the dummy lead.
By this means, when the sealing material is injected after mounting the integrated circuit component, surface tension is created in the interval between the projection and the integrated circuit component, and an excessive flow of the sealing material from the gap between the integrated circuit component and the opening can be prevented. For this reason the thickness of the sealing material can be made uniform.
(16) The dummy lead may have a bending portion. The projection may extend from the bending portion of the dummy lead.
By this means, since the difference in height between the projection and the integrated circuit component can be assured, an adequate surface tension of the sealing material can be obtained using the difference in height. For this reason, an excessive flow of the sealing material from the gap between the peripheral edges of the opening and the integrated circuit component can be prevented, and the thickness of the sealing material can be made uniform.
(17) The width of the dummy lead may be wider than a width of each connection lead.
By this means, even when the peripheral edges around the opening into which the plurality of connection leads extend is cooled, and the opening seeks to expand, this force can be withstood without dummy leads breaking.
(18) The dummy lead may be electrically insulated from the electrodes of the integrated circuit component.
By this means, no consideration of the various conditions relating to conduction in the connection of the dummy lead and the integrated circuit component is required, and the form can be made appropriate to the improvement of the bonding strength.
(19) More than half of the connection leads may be formed on the portion of the base material to which the second portion of the integrated circuit component faces.
By this means, since the majority of the connection leads can be formed on the area facing the integrated circuit component, the external dimensions of the integrated circuit device can be made smaller than in the conventional case.
(20) The first group of connection leads may be formed on the portion of the base material to which the second portion of the integrated circuit component faces. The second group of connection leads may be formed avoiding the portion of the base material to which the second portion of the integrated circuit component faces. The first group of connection leads are connected to output sides of the electrodes of the integrated circuit component. The second group of connection leads are connected to input sides of the electrodes of the integrated circuit component.
By this means, the invention can be applied to an integrated circuit component in which the number of output terminals is very much greater than the number of input terminals, such as an integrated circuit component used for driving a liquid crystal display device, for example.
(21) The integrated circuit device of the invention comprises a tape carrier for TAB having a base material, a plurality of connection leads and at least one dummy lead. The base material has an insulating property and has peripheral edges forming a rectangular opening. The connection leads extend into the opening from a pair of the peripheral edges facing each other. The dummy lead extends into the opening from one of the other pair of the peripheral edges facing each other. An integrated circuit component is positioned inside of the opening, electrically connected to the connection leads, and connected to the dummy leads.
According to the invention, after the integrated circuit component is mounted, the heated base material seeks to contract, but the dummy lead extending in this contracting direction supports the base material. As a result, breakage of the connection leads due to shrinkage of the base material can be prevented.
(22) The electronic apparatus of the invention comprises the integrated circuit device, which is mentioned above.
(23) The method of making an integrated circuit device of the invention comprises:
preparing for a base material having an insulating property, having an opening, and having a plurality of connection leads on one surface thereof, the connection leads extending into the opening;
positioning an integrated circuit component in a state where a part of the integrated circuit is positioned inside of the opening, and the remainder faces another surface of the base material with a gap therebetween;
electrically connecting the connection leads to the integrated circuit component through the opening; and
supplying a sealing material to the integrated circuit component through the opening with the integrated circuit component heated.
By this means, since the integrated circuit component is heated when the sealing material is injected, the viscosity of the sealing material is reduced, and therefore the sealing material is able to enter the gap between the base material and the integrated circuit component. After injection of the sealing material is completed, when heating of the integrated circuit component is stopped, the viscosity of the sealing material rises. As a result, the sealing material can be retained between the base material and the integrated circuit component.